Cyclic diamides of 2-chloroethylphosphonic acid as plant growth regulants

ABSTRACT

PLANT GROWTH REGULATING COMPOUNDS ARE SUBSTITUTED 2CHLOROETHYLPHOSPHONIC DIAMIDES OF THE FORMULA:   CL-CH2-CH2-P(=O)(-N(-R1)-R2)2   WHEREIN R1 IS CYCLOALKYL, R2 IS HYDROGEN OR CYCLOALKYL OR R1 AND R2 TOGETHER FORM A HETEROCYCLIC RING SUCH AS MORPHOLINE, PIPERIDINE OR PYRROLIDINE. THEY ARE PREPARED BY THE REACTION OF 2-CHLOROETHYLPHOSPHONIC DIHALIDE WITH THE APPROXIMATE AMINE OR BY THE REACTION OF EXCESS AMINE WITH A 2-CHLOROETHYL DICHLOROPHOSPHITE FOLLOWED BY REARRANGEMENT OF THE CHLOROETHYL ESTER INTERMEDIATE.

United States Patent 3,711,272 CYCLIC DIAMIDES OF Z-CHLOROETHYL-PHOSPHONIC ACID AS PLANT GROWTH REGULANTS David I. Randall and Robert W.Wynn, Easton, Pa., assignors to GAF Corporation, New York, N.Y.

No Drawing. Filed Dec. 23, 1969, Ser. No. 887,746 Int. Cl. A01n 9/36 US.CI. 71-86 9 Claims ABSTRACT OF THE DISCLOSURE Plant growth regulatingcompounds are substituted 2- chloroethylphosphonic diamides of theformula:

wherein R is cycloalkyl, R is hydrogen or cycloalkyl or R and R togetherform a heterocyclic ring such as morpholine, piperidine or pyrrolidine.They are prepared by the reaction of 2-chloroethylphosphonic dihalidewith the appropriate amine or by the reaction of excess amine with a2-chloroethyl dichlorophosphite followed by rearrangement of thechloroethyl ester intermediate.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to cyclic amides of 2-chloroethylphosphonic acids, whichcompounds are useful as plantgrowth regulators, and processes for theirpreparation.

Background of the prior art The art is aware that certain phosphoruscontaining compounds are useful as plant growth regulators. One of themost important phosphorus compounds of this type is2-chloroethylphosphonic acid which has found importance as a plantgrowth regulator, particularly in the treatment of pineapples, soy beansand other plants to control their rate of growth. The present inventionprovides a new class of phosphorus containing compounds useful as plantgrowth regulators not known heretofore, which compounds have utility inthis area equivalent to 2-ch1oroethylphosphonic acid. One of the primarycharacteristics of products of these types resides in the presence ofthe 2-chloroethyl group as this is important to the plant growthstimulating activity because it is believed that the action of thecompounds is due to the fact that they are absorbed by the plant andrelease ethylene, a known plant regulator in a form in which it can beused by the plant.

The art is aware of various nitrogen-substituted phosphonamidates butnone are suggested as having plant growth activity equivalent to thoseof the present invention. For example, in Izv. Akad. Nauk. SSSR, Ser.Khim 1966 (8), pages 165-70, is disclosed P-(2-chl0roethyl)-N,N'-tetraethylphosphonic diamide, a non-cyclic diamide which issomewhat analogous. This compound is prepared by the reaction of ClCH CHOPCl on excess diethylamine. Similarly, in Bull. Acad. Sci., Classe Sci.Chim., 1947, pages 97100, there is disclosed P-(2-chloroethyl)-N,N'-diphenylphosphonic diamide, prepared by the reaction of2-chloroethylphosphonic dichloride with aniline. In none of these priorart teachings however, is there a disclosure of the N-substituted2-chloroethylphosphonic acid diamides and in particular,2-chloroethyl-N-substi- 3,711,272 Patented Jan. 16, 1973 SUMMARY OF THEINVENTION It is accordingly one object of this invention to provide anew class of compounds comprising N-substituted 2- chloroethylphosphonicacid diamides.

A further object of the invention is to provide economical processes bywhich these products may be produced.

It is a still further object of the invention to provide N-substitutedZ-chloroethylphosphonic acid diamides which may be prepared from readilyavailable materials in an economic manner as well as procedures fortheir use as plant growth regulators.

Other objects and advantages of the present invention will becomeapparent as the description thereof proceeds.

In satisfaction of the foregoing objects and advantages, there areprovided by this invention plant growth regulators of the followingformula:

wherein R is cycloalkyl, preferably of about 36 carbon atoms, such ascyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl andcyclooctyl, R is hydrogen or the same as R or R and R together can forma heterocyclic ring selected from the group consisting of morpholine,piperidine and pyrrolidine and alkyl substituted derivatives thereofwherein the alkyl group contains 1-5 carbon atoms.

DESCRIPTION OF PREFERRED EMBODIMENTS It has been found that theabove-identified 2-chloroethyl nitrogen-substituted phosphonic aciddiamides have unique activity as plant growth regulators and may beapplied to plants such as pineapples, soy beans, tomatoes, small grainsand the like to regulate growth to thereby improve crop yields thereof.Thus, these compounds may 'be stated to be plant growth hormones as theyoperate to increase yields of the products mentioned as well as others.

The compounds of this invention are soluble in varying degrees in waterand so they can be applied to the plants in aqueous solutions composedwholly or partially of water; partial solutions include those formed ofwater and say acetone or methyl ethyl ketone. Any aqueous medium may beused provided that it is not toxic to the plant. Where any particularderivative is less water-soluble, it may be solubilized by the use ofco-solvents and the like. Also, the compounds may be absorbed on solidcarriers such as vermiculite, attaclay, talc and the like forapplication in granular form. Dusts may also be used in which case theactive ingredient(s) will be diluted with clays or other powders, forexample pyrophyllite, diatom aceous earth and attapulgite.

The compounds of this invention can be applied to the plants at aconcentration of from /2-10 lbs./ acre or higher, dependent on theparticular derivative used. A preferred rate of application ranges from2-5 lbs/acre. The phosphonic derivatives need only be applied to theplant in low volumes of water to achieve satisfactory initiation, andthis is an important advantage of this invention. Whereas it isnecessary to apply the known agents in large volumes of water, on theorder of 200400 gallons/acre, even up to 1,000 gallons/acre in the caseof ethylene, to achieve initiation, it is possible to apply a compoundof this invention in far lower volumes of water to achieve satisfactoryflower initiation. For example, the compounds of the present inventioncan be applied to 50 gallons of water at the rate of 1 lb./acre toachieve 100% flower induction on pineapplies of the Smooth Cayennevariety. The ability to apply the agent in a reduced volume of water isa great agronomic advantage because a larger acreage of plantation canbe treated before recourse to a water supply is necessary, smallerequipment can be used and costs can be reduced generally.

The diamide compound of this invention may be prepared by the reactionof 2-chlloroethylphosphonic dihalide of the following formula:

t/ opossum-1 wherein X is halogen, preferably chlorine, but it may alsobe bromine, iodine or fluorine, with an equimolar quantity of an amineof the formula:

wherein R and R are as above, in the presence of a suitable acidacceptor, the acceptor being employed to remove the hydrogen halideformed during the reaction.

Suitable amines which may be employed in the reaction includecyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine,cycloheptylamine, cyclooctylamine, as well as mixtures thereof. Alsoheterocyclic amines may be employed such as morpholine, piperidine,piperazine, pyrrolidine and the like as well as the lower alkylsubstituted derivatives thereof. The amines are pref erably employed ina solvent solution.

While the acid acceptors for the reaction may be provided by use of anexcess of the amine reactant, we prefer to use another less expensiveacid acceptor. Such acid acceptors are well known to the art. Aspreferred acid acceptors which may be employed may be mentionedinorganic acid acceptors such as alkali metal hydroxides (e.g. NaOH andKOH), alkali metal carbonates (Na CO bicarbonates (NaHCO and the like.Also alkaline earth metal hydroxides, oxides, carbonates, etc., may alsobe employed. Preferred organic acid acceptors are the tertiary aminessuch as triethyl amine, trimethyl amine, pyridine, etc. Mixtures of acidacceptors may also be employed.

The reaction is conducted in the presence of a solvent or solventmixture. Preferred solvents to be employed in the process include Water,diethyl ether, dioxane, petroleum ether, aromatic hydrocarbons (e.g.benzene, toluene, xylene, etc.), as well as mixtures thereof.

The reaction is conducted at atmospheric pressure and at a lowtemperature of about --l C. to 20 C., preferably 0 C. to 5 C. Inaddition, in a preferred aspect, each of the reactants are mixed whilecontained in the solvent. Moreover, when employing an outside acidacceptor, it is preferred if the reactants are contacted instoichiometric quantities.

The process is preferably conducted by charging each of the reactingmaterials to a portion of the solvent, and the solutions contacted atthe low temperatures mentioned. In a preferred procedure, the startingZ-chloroethyl compound is generally charged to a portion of the solvent,cooled to about C. to C. and a solution of the amine added thereto.Generally, either an excess of the amine or another acid acceptor isadded simultaneously or prior to addition of the amine.

After the materials have been mixed, the reaction mixture is generallyagitated for a short period at room temperature, any amine salt formedis removed and the resulting filtrate freed of solvent to provide theproducts of the invention.

A second procedure by which the products of the invention can beprepared is by the action of an excess of the amine on 2-cl1l0roethyldihalophosphite. In this reaction, the 2-chloroethylphosphonic aciddiamide results from rearrangement of the chloroethyl ester of thesubstituted diamidophosphorus acid which is initially formed in thereaction. This reaction proceeds by the following equation:

wherein, in the equation, X, R, and R are as defined above.

The starting material for this reaction is formed by the reaction ofethylene oxide on phosphorus trihalide (e.g. PCl to form for exampleZ-chloroethyldichlorophosphite. This starting material is then reactedwith the amine of choice at a temperature of about l0 to 20 C.,preferably 0-5 C., with the solvents and procedures discussed above forthe alternative method for formation of the products. This intermediate,2-chloroethyldiamidophosphorus acid, is then rearranged as indicatedabove, by stirring at 2030 C. to form the Z-chloroethylphosphonic aciddiamide.

It is therefore to be understood that the products of this invention maybe prepared by either of the above alternative processes of preparationor by any other suitable method.

The following working examples are provided to illustrate the compoundsand processes of the present invention.

EXAMPLE I P-(Z-chloroethyl)-N,N-dicyclopropylphosphonic diamide Therewas charged to a reaction flask 57.0 grams (0.2 mol) of a 20% aqueouscyclopropylamine solution, 50 ml. water, 16.8 grams (0.2 mol) sodiumbicarbonate, and ml. ether. The mixture was cooled to 5 C. and there Wasadded dropwise a solution of 18.2 grams (0.1 mol)2-chloroethylphosphonyl dichloride in 100 ml. ether. The mixture wasstirred at room temperature until the ether evaporated. The product wascollected on a filter and dried. Yield=34.8 grams.

The solid product was extracted twice with 50 ml. portions of methanoland filtered. The filtrate was flash evaporated at 50 viscous liquid.

C. toyield 16.9 grams of a brown EXAMPLE H Diamide from morpholine and2-chloroethylphosphonic dichloride Into a flask protected from theatmosphere with a driving tube there was charged 34.8 grams (0.4 mol)morpholine and 500 ml. benzene. At 0-5 C. there was added dropwise asolution of 18.2 grams (0.1 mol) 2- chloroethylphosphonyl dichloride in100 ml. benzene. The mixture was stirred one hour at room temperature.The morpholine hydrochloride was filtered off and washed with benzene.The filtrate was flash evaporated to constant weight. There was obtained26.0 grams of solid product melting at 9597 C.

EXAMPLE III Diamide from piperidine and 2-chloroethylphosphonyldichloride Into a flask protected with a drying tube was charged 34.0grams (0.4 mol) piperidine and 500 ml. benzene. At 05 C. there was addeddropwise a solution of 18.2 grams (0.1 mol) 2-chloroethylphosphonyldichloride in 100 ml. benzene. After stirring 1 hour at room temperaturethe piperidine hydrochloride was filtered off and washed with benzene.The filtrate was flash evaporated to constant weight. There was obtained27.4 grams of viscous brown liquid.

EXAMPLE IV P- 2-chloroethyl -N,N-dicyclohexylphosphonic diamide Therewas charged 100.0 grams (0.2 mol) of a aqueous cyclohexylamine solution,50 ml. water, 21.2 grams (0.2 mol) sodium carbonate, and 100 ml. ether.The mixture was cooled to 5 C. and there was added dropwise a solutionof 18.2 grams (0.1 mol) 2-chloroethylphosphonyl dichloride in 100 ml.ether. The mixture was stirred at room temperature until the etherevaporated. The product was collected on a filter and dried. Yield=39.8grams.

The solid product was extracted twice with 50 ml. portions of methanoland filtered. The filtrate was flash evaporated at 50 C. to yield 20.1grams of a brown viscous liquid.

EXAMPLE V Diamide from pyrrolidine and 2-chloroethylphosphonicdichloride Into a flask protected from the atmosphere with a drying tubethere was charged 28.4 grams (0.4 mol) pyrrolidine and 500 ml. m-xylene.At 0-5 C. there was added dropwise a solution of 18.2 grams (0.1 mol) 2-chloroethylphosphonyl dichloride in 100 ml. m-xylene. The mixture wasstirred one hour at room temperature. The pyrrolidine hydrochloride wasfiltered off and washed with m-xylene. The filtrate was flash evaporatedto constant weight. There was obtained 22.4 grams of solid product.

The invention has been described herein with reference to certainpreferred embodiments. However, the invention is not to be considered aslimited thereto as obvious variations thereon will become apparent tothose skilled in the art.

What is claimed is:

1. A plant growth regulating composition of matter comprising anetfective growth stimulating, flower initiating a crop increasing amountof a compound of the formula:

wherein R is cycloalkyl of 3 to 8 carbon atoms and R is hydrogen orcycloalkyl of 3 to 8 carbon atoms, and a carrier for said compound.

2. A composition according to claim 1 wherein R and R are cyclopropyl.

3. A composition according to claim 1 wherein R and R are cyclohexyl.

4. A composition according to claim 1 wherein R is cycloalkyl of 3 to 8carbon atoms and R is hydrogen.

5. A method for regulating the growth of plants which comprises applyingthereto an effective growth-regulating amount of a composition asdefined in claim 1.

6. A method according to claim 5 wherein said composition is applied ata concentration of about 0.5 to 10 lbs. of said compound per acre ofplants.

7. A composition as defined in claim 1 wherein said carrier is anaqueous medium.

8. A composition as defined in claim 1 wherein said carrier is a solidmaterial.

9. A method for regulating the growth of plants which comprises applyingthereto, at a rate of about 0.5 to 10 lbs. per acre of plant, a compoundof the formula (ll-CHzCHz- 6/1969 Republic of South Africa JAMES O.THOMAS, 1a., Primary Examiner U.S. Cl. X.R.

7188, 92, 94, 260246 B, 247.5, 268 K, 268 H, 293.87, 293.63, 326.85, 551P

